This invention relates to the lubrication of glass pressing apparatus, and more particularly to an improved method and composition for the lubrication of such apparatus. The method and apparatus can be used to produce a pressed glass article or to produce a parison from which a finished article can be blown.
Glass containers, e.g., tumblers and bottles, are frequently produced in an IS machine by placing a charge of heat-softened glass, usually called a "gob", in a mold cavity, advancing a plunger into the mold to form the gob into a parison, transferring the parison to the cavity of a second mold, and blowing the parison to the shape of the second mold. Typical high-speed, modern manufacturing processes employ a plurality of pairs of parison and second molds. Such operations require lubrication of the interior surfaces of the parison mold to prevent, or at least minimize, sticking of the glass to the molds and to minimize wear of the molds.
Various techniques have heretofore been used to lubricate mold surfaces of glass pressing apparatus. For example, one practice is to spray kerosene, light oils, or the like onto the mold surfaces to deposit a lubricous coating. The surfaces have also been swabbed periodically with kerosene, light oil, and the like. These materials, however applied, are ignited by contact with molten glass in the mold or by an external spark or pilot light; their combustion produces carbonaceous residues which are lubricous in nature. Liquefied petroleum and other hydrocarbon gases have also been used by spraying techniques for the lubrication of glass pressing apparatus. Kerosene, light oil, and hydrocarbon gases that have heretofore been used are comparatively undesirable, either generally or when the lubrication of deep parison molds or of molds for pressing of handled ware is desired. The combustion of hydrocarbon gases that have been used is difficult to control in deep parison molds and handled pressing molds; the consequence of insufficiently controlled combustion is inadequate and incomplete lubrication. Atmospheric pollution is caused by the use of kerosene, light oil, and the like.